1. Field of the Invention
The present invention relates to an automatic transmission controller applied to a hybrid vehicle which includes an engine, a traction motor, and a generator motor, and can travel by the driving force from the individual traction motor, or the driving force from the engine.
2. Description of Related Art
Recently, there is known a hybrid vehicle wherein one of the pair of front or rear main driving wheels are driven by an engine and the other pair of front or rear sub driving wheels are driven by a motor that is connected to a battery.
In such a hybrid vehicle, the amount of fuel consumption and the exhaust gas can be decreased by selectively using the engine and the motor according to the operating state.
As this kind of hybrid vehicle, there is a vehicle wherein the deceleration energy is regenerated by a single or a plurality of motors provided in the vehicle, and used as the energy at the time of re-acceleration, to thereby increase the fuel economy. Furthermore, there is a vehicle wherein the regenerated energy is used for traveling by an individual motor in order to further increase the fuel economy.
For example, in Japanese Unexamined Patent Application, First Publication No. H09-289706, there is proposed a technique where, in a hybrid vehicle which can travel in various traveling modes such as individual motor traveling mode, engine traveling mode, and the like, vehicle mounted apparatuses can be driven even in the case in which the engine is stopped under predetermined traveling conditions.
Moreover, in Japanese Unexamined Patent Application, First Publication No. 2001-206088, there is proposed a technique where, in a hybrid vehicle which can travel by an individual motor, an individual engine, or a combination of the motor and the engine, hydraulic pressure for controlling an automatic transmission can be ensured even in the case where an abnormality arises in a multiplex communication system.
However, in the conventional hybrid vehicle, the engine is stopped when individual motor traveling (EV traveling) is performed. As a result, an oil pump mounted on the automatic transmission is not driven, so that the shift position of the automatic transmission is not fixed during the EV traveling.
Therefore, it is necessary to reset the shift position corresponding to the vehicle speed or the accelerator pedal, when shifting from the EV traveling to the engine traveling or the motor-assisted traveling. As a result, when shifting from the EV traveling to the engine traveling (engine traveling or motor-assisted traveling), the output power is not transferred to wheels until the oil pump has been activated by engine startup to increase the hydraulic pressure in the automatic transmission and a clutch in the shift position is fastened. Therefore, when shifting from the EV traveling to the engine traveling, there is a problem in which a time lag occurs until the driving force required by a driver is output, so that the engine output can not be smoothly increased, thus reducing drivability.
It is an object of the present invention to provide an automatic transmission controller for a hybrid vehicle wherein the driving force can be quickly output while decreasing the fuel consumption, and drivability can be improved.